Forced air recirculation floor furnace



Nov. 29, 1955 R. c. HAUCK ETAL 2,725,051

FORCED AIR RECIRCULATION FLOOR FURNACE Filed Jan. 6, 1953 INVENTOR. ROY C. //A UC/f United States Patent 2,725,051 RECIRCULATION FLOOR FURNACE Roy C. Hauck, Plainsboro, and Albert L. Nathan, Trenton, N. J.; said Hauch assignor to Delta Heating Corporation, Trenton, N. 3., a corporation of New Jersey Application January 6, 1953, Serial No. 329,878 1 Claim. (Cl. 12611(l) This invention relates to space heaters and is directed particularly to a new type of floor type furnace adapted to be fired by oil or gas and capable of economical construction and eflicient operation.

Many types of furnaces and space heaters have been developed heretofore but they are, in general, very bulky and expensive to build and install, and are not always eflicient in operation. Moreover, floor type heaters have not always been designed to eflect recirculation of the air within an enclosure and have, in some instances, merely heated and circulated external air. With such constructions the air in an enclosure tends to stratify and stagnate and a greater amount of heat must be supplied to raise the temperature of the external air than is neededto reheat the air drawn from a heated enclosure.

In accordance with the present invention these objections to constructions of the prior art are overcome and a space heater provided which is relatively small and economical to produce and install, and at the same time is efiicient and inexpensive in its operation. These advantagesare preferably attained by a novel arrangement of a combustion chamber and heat exchanging passages which are assembled within an air circulating chamber and adapted to be suspended or otherwise supported directly adjacent the floor of a room or space to be heated. In the preferred form of the present invention, an outer air circulating casing supports and surrounds the combustion chamber in a manner to permit ready installation while protecting and absorbing heat from the highly heated elements of the assembly. The arrangement of the combustion chamber and air heating passages within the casing further insures eflicient combustion and heat exchange while reducing pulsations and vibration incident to the combustion.

One of the objects of the present invention is to reduce the cost and increase the efliciency of floor type space heaters.

Another object of the invention is to provide improved air circulation and heat exchange within a floor type space heater.

A further object of the invention is to provide a floor type space heater with a casing having a novel arrangement of means for supporting the elements and insuring heat exchange and air circulation within the casing for more eflicient operation of the assembly.

These and other objects and features of the present invention will appear from the following description thereof in which reference is made to the figures of the accompanying drawing.

In the drawing:

Fig. l is a vertical sectional view through a typical form of floor type space heater embodying the present invention;

Fig. 2 is a horizontal sectional View of the construction illustrated in Fig. 1 taken on the line 22 thereof;

Fig. 3 is a vertical sectional view of the construction illustrated in Fig. 1 taken on the line 33 thereof; and

Fig. 4 is a perspective illustrating the assembly shown in Figs. 1,2 and 3.

In that form of the invention chosen for purposes of FORCED AIR illustration, the assembly is designed for use in combina-' burner. part of the present invention. The unit is designed for The burner itself is not illustrated and forms no 2,725,051 Patented Nov. 29, 1955 insertion through asuitable opening in a floor 2 and is provided with an outer casing 4 which, as shown, may be formed at its upper edge with a laterally projecting flange 6 designed to overlie the edges of the floor about an openice ing within which the unit is located. The top of the cas' ing 4 is open and is provided with a suitable grill 8 or other means providing for ready flow of warm air upward therethrough into the room or space to be heated. The

grill 8 further serves to admit air from the room to the unit adjacent the outer casing 4. Ifdesired, the air also may be admitted to the outer casing near the lower portion thereof from other rooms or distant points throng the air return duct 10.

Within the outer casing 4 there is located an inner shell 12 which encloses a vertically disposed combustion chamber 14 mounted in heat exchange relation with the bottom wall of the shell and preferably lined with fire-brick or other refractory material 16. A burner tube 18 communicates with the combustion chamber by passage in heat exchange relation through the space between the outer casing and the shell and is provided on its outer end with a flange 20 welded or otherwise secured to the outer casing 4 and designed to receive and preferably be secured to the gun or discharge tube of an oilfor gas burner. The upper portion of the combustion chamber 14 com municates with the hot gas chamber 22 through which the products of combustion flow about the air tubes 24 and 26 to a flue passage 28 designed to be connected to a chimney or stack. The flue also extends in heat exchange relation through the space between outer casing and shell. The flue also may be provided at its outer end withan attaching flange, as shown at 39, which is welded or otherwise secured to the outer casing 4.

An intermediate casing 32 is located between the outer casing 4 and the shell 12 and cooperates therewith to provide air inlet passages 34 and hot air passages 36' between the outer casing and the shell. Air from the room to be heated, therefore, may flow downward through the grill 8 and the passages 34 to the lower portion of the outer casing. It then flows upward through the opening 37 in the bottom plate 38 of the intermediate casing 32, thence outwardly under the bottom of the shell in heat'exchanging relation with the bottom of the combustion chamber as well as upwardly through the tubes 24 and '26 within the shell. The air flowing upward about the heating chamber through the hot air passage 37 and through the hot air tubes 24 and 26 emerges from the open, upper end of the intermediate casing 32 and is directed toward the central portion of the. grill 8 by deflecting vanes 40.

Circulation 'of the air in the manner described is preferably aided orinduced by means of a fan 42 driven by a motor 44. The motor is preferably mounted on the bottom plate 46 of the outer casing 4, whereas the fan 42 is located in or adjacent to the opening 36 in the bottom plate 38 of the intermediate casing 32. In this way, a vigorous and positive circulation of the air through the unit may be assured in a manner to provide eflicient heat exchange with the surfaces of the shell 12 and the hot air tubes 24 and 26. At the same time, the air to be heated may be drawn from the room to which heat is being supplied or it may be drawn from a remote point through the air return duct 10.

The hot air passages 24 and 26 which extend through the shell 12 are so arranged as to insure effective baflling of the hot products of combustion in their travel from the combustion chamber 14 to the flue 28. In the preferred construction shown, those tubes 24 which are closest to the combustion chamber'14 are positioned relatively close together, say about one-half inch apart,

whereas the secondary tubes 26 which are more remote from the combustion chamber are spaced farther apart,

say about one-inch apart or at about twice the spacing of 3 the tubes' 24. The hot products of combustion" in flew: ing between the tubes 24 emerge in a jet like manner which creates eddy-currents and induces lateral flow of the products of combustion by a venturi action into contact with the secondary tubes 26. The batflingand turbulence thus established within the space between and about the tubes 24 and 26 serves to retard the flow of the products of combustion for effective heat exchange without creating material back pressure upon the gases passing to the chimney or stack through the flue opening 28. The flow of air through the hot air passages 36 and through the hot air tubes 24 and 26 also takes place in a turbulent manner under the action of the fan 42 particularly when the elements are arranged in an unsym-' metrical manner as shown in the drawings. Therefore, the maximum heat exchange takes place between the products of combustion and the air circulating through the tubes 24 and 26 and about the shell 12 through the surrounding hot air passages 36. As a result, the temperature of the gases passing to the stack is materially reduced, whereas the temperature of the air flowing upward through the grill 8 is increased and a highly efiicient heat exchanging unit is provided.

In constructing the unit illustrated, the outer casing 4 is preferably lined with a heat insulating material such as' asbestos or the like which may be further lined in its inner surface with a heat reflecting material such as.

aluminum foil. The lower portion of the side walls of the casing 4 maybe formed as shown with an inwardly extending flange 48 adapted to be engaged by the downwardly turned edges 50 of the bottom plate 46 of the outer casing so as to support and position the bottom plate and permit easy assembly of the elements. The edges 50 further serve to hold the bottom plate sufliciently elevated to prevent injury to the motor 44 and its retaining bolts '52 when the unit rests on a flat surface or is packed in a crate for shipment. The edges 50 also provide a convenient surface for welding or applying'ibolts for'se'curing the bottom plate 46 in place within theside walls of the outer casing 4.

The bottom plate 38 of the intermediate casing may be secured to the side walls thereof in a similar manner but asshown it is' provided with an upwardly turned marginal flange 54 for welding or bolting. to the side walls of the intermediate casing. The intermediate casing is supported in place within the outer casing 4 by means of; the burner tube 18 and the flue passage 28. Howevenifdesired, additional support may be provided by the external portion of brackets 56 which are welded to the bottom plate 46 of the outer casing and secured to the bottom plate 38 of the inter-mediate casing.

The shell 12 is supported within the intermediate casing 32 by means of brackets 56 which project upward and are secured to the sides of shell 12. The brackets may if desired be mounted on the bottom wall of casing 32 or be mounted on the bottom wall of casing 4 and pass: through the bottom wall of casing 32. Any suitable number of brackets may be provided for this purpose and they may be arranged as required for any installation, The elements of the assembly can thus be quickly and easily arranged and assembled; and each;'of the elements may be formed independently andsecured inplace by welding or otherwise.

The upper portion of theshell 12 preferably is provided with an access door 60 having an inwardly spaced heat deflecting bafiie 62 for protecting the door from excessive temperatures while permitting the door to be opened for inspection and cleaning of the combustion chamber or for replacement ofthe refractory elements 16 when required. Side brackets 64 secured to the inner surface of the shell 12 serve to hold the refractory members 16 in .place and a similar bracket 66 maybe securedto one or more of the" air tubes to aidinholding the combustion chamber and its refractory lining in position.

The construction thus provided is small and compact and yet, at the same time, it may be produced from sheet material or other material without special and expensive forming operations. The various elements may be assembled and secured in place by welding or otherwise, and the whole unit can be dropped into place through an opening in the floor of the room to be heated. The gas or oil burner may be suspended from the floor 2 or attached directly to the flange 20 on the outer end of the burner tube 18. At the same time, the gun or discharge tube of the burner may be spaced orotherwise arranged with respect to the flange 20 in a manner to overcome objectionable pulsation due to the coinbusti'on taking place within the combustion chamber 14.

While a preferred form of heating unit has been shown in the drawing and described above it, will beapparent that numerous changes and modifications can be made in the form, construction and arrangement of the various elements of the assembly. It should, therefore, be understood that the particular embodiment of the invention herein shown is intended to be illustrative only and is not intended to limit the scope of the invention.

We claim:

A floor type heating unit adapted to be fired by an independently mounted flame projecting oil or gas burner and comprising an outer casing which is open at the top' and closed at the bottom and provided at the top with an outwardly turned flange for supporting the uriit in suspended relation beneath an opening in a floor, a heating shell located within said outer casing and including therein a vertically disposed refractory lined combustion chamber which is open at the top and mounted within and adjacent one side of said shell and in heat exchange relation with the bottom wall of said shell, said heating shell having a portion extending laterally from the cornbustion chamber and having substantially vertical air heating tubes extending through said portion, an intermediate casing located between and in spaced relationto said outer casing and said heating shell and provided with an open top and a closed bottom, said bottom being apertured substantially centrally thereof to receive a fan therethrough, said intermediate casing cooperating with the outer casing and the heating shell to define an air passage extending from marginal portions of the open top of the unit to the lower portion of the unit and thence inwardly to the aperture of said bottom of said intermediate casing, thence outwardly under said chanther and tubes and upwardly about said heating shell and through said air heating tubes back to the central portion of the open top of the unit, a fan mounted within the aperture of the bottom of said intermediate casing for positively circulating air laterally therethrough in all horizontal directions, a burner tube extending horizontally from the exterior of the outer casing through said intermediate casing to and communicating with said cornbustion chamber, means on the exterior of said outer casing at the end of said burner tube for attachment of a flame projecting burner thereto, and a horizontal flue extending from the laterally extending portion of the heating shell to the exterior of the outer casing, the air tubes being located between said shell and said fiue so that products of combustion passing to said flue from said chamber will flow in heat exchanging relation with said air tubes.

References Cited in the file of this patent UNITED STATES PATENTS 71,244 Thatcher Nov. 19, 118 67 1,936,003 White Nov. 21, 1933 2,023,136 Herbster Dec. 3, 19575 1 2,089,407 Norris -t Aug. 110.,- 1931 2,694,456 Lattner' Sept. 28; 1937 2,517,446 Ryder et a1. Aug. '1, 1950 2,581,145 Roberts Jan; 1, 1952 

